Upcasting in Java

beginner· OOP · Inheritance

Problem

Upcasting means storing a subclass object in a variable declared with a parent type — Java allows this automatically, since every subclass object is guaranteed to support everything the parent type promises.

Assign a Manager object to an Employee-typed variable, and show that only Employee's own members are reachable through it.

Input

Employee e = new Manager();

Output

Employee is working

Java Program

Java

class Employee {
    void work() {
        System.out.println("Employee is working");
    }
}

class Manager extends Employee {
    void manageTeam() {
        System.out.println("Manager is managing the team");
    }
}

public class UpcastingDemo {
    public static void main(String[] args) {
        Employee e = new Manager(); // implicit upcast — no cast syntax needed
        e.work();
        // e.manageTeam(); would not compile: Employee's type doesn't declare manageTeam()
    }
}

▶ Run Code

Output

Employee is working

Core Logic

Declaring the variable as the parent type while assigning a subclass instance to it happens automatically in Java, with no cast needed.

How It Works

1Employee e = new Manager(); upcasts implicitly — no explicit cast syntax is written, since going from a subclass to its parent is always safe.
2e's declared type is Employee, even though the object it actually refers to is a Manager.
3Calling e.work() works fine, since work() is declared on Employee itself.
4A call like e.manageTeam() would fail to compile — manageTeam() only exists on Manager, and the compiler only allows calls that the declared type Employee actually promises.

Even though e refers to an actual Manager object, e.work() prints "Employee is working", since Manager doesn't override work() here.

💡

Key Point: Upcasting narrows what's accessible through a reference, not what the object actually is — the underlying object is still fully a Manager, but the Employee-typed reference can only see Employee's own members.

Key Concepts

upcastingimplicit conversionreference type vs. actual type

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toString() Override

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